1. Field of the Invention
The present invention relates generally to audio speaker systems, and more particularly, to an omni-directional stereo speaker adapted to be positioned in free space away from reflecting walls so as to achieve a more realistic stereo sound than is otherwise obtainable with box-like speaker enclosures positioned adjacent a wall Or other flat surface.
2. Description of the Prior Art
Conventional speaker enclosures for reproducing so-called stereo sound attempt to simulate a pair of spaced point sources emanating from a flat vertical wall. Thus, the typical stereo speaker configuration comprises a pair of rectangular shaped boxes each having a speaker, or a multiplicity of speakers mounted on the front face thereof, the pair being positioned in a spaced manner against a vertical wall surface. Each speaker, in turn reproduces a slightly different audio signal, i.e. a right channel and a left channel, which signals become blended in the space between the speakers and away from the wall. A listener positioned in that space will perceive the blended signal as having both lateral and depth components and this effect, known as the "stereo effect" will impart a sense of realism to the reproduced sound. When a pair of spaced "stereo" speaker boxes or enclosures are placed against a flat reflecting surface such as wall, for example, an arrangement typical in a great many installations, portions of the sound wave being reproduced by each speaker are reflected from the wall giving rise to interference patterns with respect to the sound being directly radiated into the listening space. The interference patterns result in unintended reinforcement and cancellation of portions of the radiated sound which, in turn, produces a form of distortion, the net effect of which is to lessen the extent of realism of the reproduced sound, and produce a flattened sound stage. For example, musical instruments which should be perceived or heard as being located in an orchestra on the left often seem to wander back and forth across the sound stage. Similarly, a vocalist, who should be in the center of the sound stage, might sound as if he or she is on the left, or the right, or worse yet, suspended in space unnaturally high up on the wall behind the speakers.
In order to ameliorate this problem, various prior art solutions have been proposed. Some speaker designs feature "bi-polar radiation," an arrangement where a speaker, or a plurality of speakers is mounted on the back of the enclosure in addition to the speaker or speakers mounted on the front surface of the enclosure. In such cases, it is usually necessary to move the speaker enclosures away from the wall and into the listening area to an extent where they undesirably interfere with furniture placement in the room. In U.S. Design Pat. No. 281,316 there is shown a speaker enclosure having speakers mounted on the adjacent sides of a rectangular box-like enclosure. Such a design requires that the speakers, for optimal performance be placed in the corners of a room. Similarly, in U.S. Pat. No. 3,720,787, a globular shaped housing having a plurality of speakers mounted on the spherical surface thereof is described. In yet another example, namely U.S. Pat. No. 4,890,689, there is shown a twelve-sided housing wherein each of the sides is concavely shaped to "horn-load" a speaker mounted thereon. None of these patented designs is completely effective however in achieving an omni-directional stereo speaker system that is capable of producing a realistic point source stereo image yet be cost effective and therefore readily available to the consuming public.
The foregoing disadvantages are overcome by the unique omni-directional stereo speaker of the present invention as will be made apparent from the following description thereof. Other advantages of the present invention over the prior art also will be rendered evident.